Central Bureau for Astronomical Telegrams
IAUC 5522: Mkn 421; N Cyg 1992
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 5523
Circular No. 5522
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
MARKARIAN 421
T. C. Weekes communicates the following on behalf of the
Whipple Observatory Gamma Ray Collaboration: "TeV gamma-rays have
been detected from the BL Lac object Markarian 421 by the Whipple
Observatory Gamma Ray Collaboration. The observations were made
with the high-resolution imaging camera on the Whipple Observatory
10-m optical reflector between Mar. 24 and May 8. A flux was
detected in 409 min of observation at the 5-sigma level. The energy
threshold was 0.5 TeV and the flux was 1.2 x 10E-11 photons cmE-1
sE-1 (0.24 that of the Crab). There was no evidence of variability
during the observations. The TeV gamma-ray source is located by
the camera within 6' of the known position of Mrk 421. This
positional agreement, coupled with the previous tentative identification
by the EGRET/Compton Gamma Ray Observatory group at GeV energies
(IAUC 5470), makes alternative identifications unlikely. During
this same observing interval, no TeV flux was detected from 3C
279, PKS 0528, QSO 0836, or 4C 38.41, all of which have been
detected by EGRET."
NOVA CYGNI 1992
S. J. Austin and S. G. Starrfield, Arizona State University; R.
M. Wagner, R. Bertram, B. M. Peterson, and M. Houdashelt, Ohio
State University; and S. N. Shore, Goddard High Resolution
Spectrograph, Computer Sciences Corporation, report: "Optical spectra
have been obtained of Nova Cyg 1992 using the OSU CCD spectrograph
on the Perkins 1.8-m telescope at the Lowell Observatory at weekly
intervals since the beginning of March. The nova has exhibited
considerable evolution in its appearance over that time period.
The initial spectra were characteristic of an optically thick gas
with permitted lines of the abundant elements as reported by
Andrillat and Houziaux (IAUC 5467). The density of the expanding
material has now decreased to where forbidden lines are becoming
the dominant features in the spectrum. Our most recent spectrum,
obtained on May 11.4 UT (range 330-860 nm, resolution 1 nm), shows
strong emission lines due to [Ne III] 386.9 and 396.8 nm; [O III]
500.7, 495.9, and 436.3 nm; [O II] 732.5 nm; the Balmer series of
hydrogen; He I 447.1, 597.6, 667.8, and 706.5 nm; He II 468.6 nm;
N III 464.0 nm; and O I 844.6 and 777.4 nm. The FWHM of H-beta was
about 2050 km/s. The observed intensity ratio, F([Ne III])/F(H-
beta) was about 3.3. The strength of the neon lines implies that
this nova may be a member of the ONeMg class of novae and further
monitoring is encouraged."
1992 May 16 (5522) Daniel W. E. Green
Read IAUC 5523
Our Web policy. Index to the CBAT/MPC/ICQ pages.
